Antenna mast base



N. LEE

ANTENNA MAST BASE Filed Feb. 1 1944 g MI llllLlurT INVENTOR. NORMAN LE ATTORNEY l9 Patented Sept. 9, 1947 wNorman 1 Lee; Red :-':Bank, N. .J.; iassignor to the United States (if America; as'representedby the Secretary of War -'-Application February 11, 1944; Serial "No. 521,964

. 2 :Glaims.

. $.Theinvention described hereinmaybemanu- .factured. and..used .byor for the Government for governmental purposes, without .the payment to me of any royaltythereon.

f. This invention relates to flexiblemast basesand more particularly to mast bases of laminated cantileverv spring construction.

Current practice inflexible mastbase construction has been of the helical coil-springtype This type. of mastbase has been, of necessity, heavy enough to withstand the bending action to which it is subjected Without assuming a set position.

Helical spring construction beingbulky has considerable capacitance to ground. In some cases this capacity reachesvalues approximating 20 to 30 micromicrofarads." Capacity of this order has the" effect of reducing the field strength in transmissionof signals. Helical springs also have inductance and changethe' electricaljadjustments n flexing. "This. is usually manifested in. detuning and noise.

' It is well understood in the 'art'that the reduction of; capacitybetween the base of anan- "tenna and the mobile unit supporting it' will increase the field strength. Invaddition' to reducing the capacity; to" ground this invention also provides a decrease in weight:on"thei"mast base,

a reduction in Wind resistance; andthe elimination of inductive changes.

Itis, therefore, an-object of this invention to provide a mast base for mobile use capable" of withstanding a deformation of 90' degrees; from a vertical position, withouttaking a permanent set. I Aiurther object isto-providea mast'baseof cantilever spring construction.

A still furtherobject is to provide a mastbase having good damping-characteristics.

. A' still furtherobject is to provide a mast'base that. will be very durableand'capable of'sustaining impact. and vibration.

Another object is .to provide a mastbase having .a minimum ofcapacitance toground.

A' still further object is to provide a .mast: base that will complement the elastic characteristics of the whip. antenna and provide a durable mechanical system.

A furtherobject is to provide a mastbase having reduced weight and wind resistance .and 0ffering a very small surface as atarget tosm'all These and other objects will become apparent irom'the following description of the illustrative embodiments of'the invention shown in the accompanying drawing, the invention residing in 56 (Granted undenthe act of. amended April 30, 1928;

.March 3,. 1883,. as 370 O. (EL-757) .the novel method; steps, .elements, arrangement of. parts: in cooperative relation, as hereinafter vpointed out in the claims; and exemplified in the practical: "embodiments. of the structure herein described as'follows.

1 Figure :1' isa vertical cross-sectionaliview of the invention completely: assembled and mounted on a support.

-.F.igure 2 is avhorizontal:.cross sectional View taken al'ong the line-2-2 of Figure 1.

Figure 3-is a vertical cross-sectional-fragmentary.-vi-ew' of a variation of theiastening-me'ans of -the invention.

- Eigure l is an elevationalview; partly cut-away and: sectioned,- of a: binding post adaptor.

. vReferringsnow. more particularly. to. Figures 1 ;'=L1'1d 2, theassembly illustrated embodies-the pres- ..ent invention ina preferred torm: A plurality of :means to-bedescribed further.

piano wires lllorwi-res of similar elasticity are disposed in juxtaposition to each othergthe-lower ends oftsaid-wires l0 are constrainedby suitable along.- The upper ends. ofisaidwires are-free to take UDChGiIxOWIl characteristic .length, when-bent, by sliding one 25' strandof piano wire with thestrength-and restoring. :force on. the .othen.

.wire'si I 0 are providedior by a recess In. effect,-the flexibility of asingle of thebundle is obtained.

1 Theconstraining. means..for.-the p1urality. of [4 into which the constrained enact the plurality of wires I i] are .affixed by welding. or .othersuitable means. The recess?! 4 heretofore.

mentioned is longitudinallydisposed in theaupperend ofanelongated member- 12. J As illustrated. in Figure 1, member I2 i so machined that it has varying circumferences which provide annular shoulders l5 and it and theirusewill be described hereinafter.

longitudinally disposed in elongated member 23.

""Thejupper ends of. the plurality. of wiresl i0 are placed withina-recess" 25 which has a. .sumcient clearance to per'rnitthe longitudinal movement of the individualwires lOIIThereces's-lfi is the. lower end of. an Longitudinally disposed in the upper portion! of the elongated member 23 is a recess 24 within which is placed, a' distance "therein, a tubularsmember'flfi having. circum "scribed'. thereon"several rolled threads' 21. An: aperture 28. radially disposed in they upper part'of the member 23am in juxtaposition to the rolled .threads 2'! eithetubular member"'26, is provided to permit "soldering the said tubular member'ZB to the. insidesurface'of the recess- 24. Leading from the lowerend of the recess'24 is an aperture 23A radially disposed in theelongated member 23 and providing a means of drainage.

Leading to the upper end of the recess 25 is an aperture 29 radially disposed in the member 23 and providing means for lubricating, through this. aperture, the plurality of wires l0.

Elongatedmember23 is so machined that it provides an annular shoulder 8 the purpose of which will be described hereinafter. Inclosing the plurality of wires Ill, and being the means of coupling the upper elongated member 23 to the lower elongated member I2, is a flexible sheath 20. Sheath 2D is attached to the lower portion of the member 23 and the upper portion of the elongated member I2 by soldering or other suitable means. It will be seen now that the shoulders 8 and I6 determine the permissible distance, that the members 23 and I2, can enter the flexible sheath 20 so as to facilitate the soldering operation.

As an additional precaution in maintaining the assembly intact, ferrules 2| and 22 are affixed, at the junction of the flexible sheath 20 and elongated member 23 at one end and the junction of the sheath and elongated member l2, at the lower end by swaging, soldering or other suitable means well known to those skilled in the art.

To eliminate the possibility of moisture entering the recesses 25 and I4, within which the plurality of wires l are disposed, a Neoprene or other equally non-hygroscopic covering 30 is provided and is bonded to the outer surface of the assembly comprising a portion of the ferrule 22, all of flexible sheath 20, and a portion of ferrule 2|.

Means for fastening the invention to the supporting member 9, and retaining in position thereto the entrance insulators l1 and I8, is an internally threaded recess longitudinally disposed within the lower portion of the elongated member I2 and into which is threaded a bolt l9 and this bolt l9 when drawn up tight into the recess |3 will maintain the entire assembly, Figure 1, in a vertical and rigid position.

A washer 3| of linen and a phenolic condensation product disposed between the shoulder l5 of the elongated member I2 and the upper portion of the insulator I'I provides a means for preventing an undue strain on the insulator ll when same is drawn tight against the supporting member 9, In a similar manner a washer 32 of linen Bakelite or material of equal composition, is disposed between the washers ISA and the lower portion of the entrance insulator l8. In addition a channel 32A, diametrically disposed in the upper plane surface of the washer 32 and immediately contiguous to the lower end of the entrance insulator I8, provides a means for drainage.

An internally threaded aperture longitudinally disposed in the head of bolt I9 is provided for the insertion of a standard binding post.

Disposed on either side of the supporting member 9 and immediately contiguous to the lower surface of entrance insulator l1 and the upper surface of entrance insulator l8 are washers HA and |8A which are used to prevent the entrance of moisture at these junctions.

Figure 2 indicates more clearly the disposition of the plurality of wires [0 which constitute a novel feature of this invention together with those components encompassing the said plurality of wires, as described heretofore.

A variation of the fastening means is illustrated in Figure 3. The arrangement of the plurality of wires I0 is similar to that described as Figure 1. In this arrangement the bolt I9 is replaced by member 33 externally threaded at its upper portion and fastened to the lower entrance insulator I8 by means of a staked nut 31. Longitudinally disposed at the lower end of the member 33, a distance therein, is a recess 38 the purpose of which will be described further along. The member 33 has been machined to provide an annular shoulder 39. A ferrule 31A having an annularly extruded portion 43 at; its upper end is slipped over the lowermost portion of the member 33 and placed against the shoulder 39 of the said member 33. The ferrule 31A is composed of a dielectric material and prior to sliding the said ferrule 31A over the aforementioned lower end of the member 33, said lower end is burred and cemented to prevent the said ferrule 31A from slipping off under pressure. An externally threaded annular member 36, burred on its inner surface is slipped over the outer surface of the ferrule 31A and cemented in place, A washer 34 is disposed contiguous to the annular extruded portion 43 and the upper portion of the externally threaded annular member 33, and serves to prevent the entrance of moisture. A washer 4| inhibits the entrance of moisture to the inner cavity of the insulator l1 and is held in place by the shoulder 42 against the said insulator H.

The aforementioned assembly illustrated in Figure 3 and particularly that portion of the construction at the lower end of member 33, is provided for the attachment of a coaxial cable.

Figure 4 illustrates a binding post adaptor which would permit the substitution, of a single conductor feed (not shown) for a coaxial cable. The lowermost portion 45 has an aperture 46 radially disposed to permit the entrance of the feed wire (not shown) from the transmitting or receiving equipment. Extending downwardly from an internally threaded cup 41 and being a part thereof is an externally threaded member 48 which fits into the member 45. Placing the feed wire (not shown) in the aperture 46 and rotating the member 45 serves to clamp tight the feed wire (not shown). Centrally disposed within the cup 41 and extending upwardly from the bottom thereof is a cylindrical contact 49 of such diameter that it has good contact when inserted in the recess 38, Figure 3.

The ability of ordinary spring wire of small diameter to bend elastically to a comparatively small radius and return to its original shape is well known to those skilled in the art. It is this ability of the small spring wire to resume its original form that is taken advantage of in this present invention together with the cantilever principle of suspension.

In essence, the cantilever spring is composed of a bundle of small diameter spring wires, such as piano wire, all of which are fastened at one end and free to take up their characteristic lengths, when bent, by sliding on one another. In effect, the flexibility of a single strand of piano wire with the strength and restoring force of the entire bundle is obtained. Alternatively, the bundle of wires need not be restrained at either end if they are completely inclosed as illustrated in Figure 1.

Desirable in another respect is the rubbing of.

the individual wires on one another when bent. This produces friction and tends to stop the mast base from oscillating excessively when released from the deformed condition. The damping effect can be varied by packing the wires more tightly or by the use of greases of different viscosity characteristics.

The construction of the invention is simple. Its dimensions are small enough to reduce the capacity to ground effects considerably, yet, more rugged and much lighter in Weight than conventional mobile mast bases. In addition to this feature, by eliminating the helical coil spring, changing inductive values are eliminated.

While there has been described What i at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A mast base, comprising a plurality of piano wires in slidable contact with each other, an elongated metal member of cylindrical configure tion, said elongated member having a recess longitudinally disposed at one end therein and an internally threaded recess longitudinally disposed at the opposite end of said elongated member, another elongated metal member of cylindrical configuration having a recess longitudinally disposed at one end therein, and a recess longitudinally disposed at the opposite end thereof, a tubular member disposed within the recess of the aforementioned elongated member and having a rolled thread circumscribing same and disposed a determined distance from the end thereof, means for aflixing the aforementioned tubular member to the inner surface of the recess in the elongated member, a bolt having an internally threaded recess longitudinally disposed in the head thereof and means adapted to insulate the entire assembly from a supportin structure.

2. A mast base comprising a plurality of piano wires, an elongated metal member of cylindrical configuration, said elongated member having a recess longitudinally disposed at one end therein and an internally threaded recess longitudinally disposed at the opposite end of said elongated member, another elongated metal member of cylindrical configuration having a recess longitudinally disposed at one end therein, and a recess longitudinally disposed at the opposite end thereof, a tubular member disposed within the recess of the aforementioned elongated member and having a rolled thread circumscribing same and disposed a determined distance from the end thereof, means for afiixing the aforesaid tubular member to the inner surface of the recess in the elongated member, together with a bolt having an internally threaded recess longitudinally disposed in the head thereof.

NORMAN LEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,930,926 Doane Oct. 17, 1933 1,910,226 Austin May 23, 1933 2,012,842 Whitted Aug. 27, 1935 2,346,426 Hait Apr. 11, 1944 2,311,427 Winkelmeyer Feb. 16, 1943 FOREIGN PATENTS Number Country Date 455,291 Great Britain Oct. 16, 1936 301,865 Great Britain Feb. 3, 1930 347,394 Great Britain Apr. 30, 1931 77,584 Sweden 1933 

